A great photo with clarity to match.
4 Union Soldiers Seated In A Half Plate Ambrotype. These four seated federal soldiers pose wearing their frock coats, with the two in the center wearing forage caps while the outside men are wearing what appears to be modified Hardee hats. The insignia is clearly infantry, but the regimental number is blurring, If I had to guess it looks like 98 or 99. Note the canteen on the ground below the second from right, and a rain cover for a cap lying close by. The second soldier from the right also has what appears to be a large safety pin? Upper and lower emulsion has small scratching from the mat.
Very clear and more so than my poor effects show. The case is leatherette.
Both are fine to excellent.
A great image!